The tribe planned to begin offering Texas Hold 'Em and Omaha poker on Friday at the casino, which is south of the city of Coeur d'Alene and draws heavily from the Spokane market.

Otter and Wasden said the tribe was in violation of the Idaho Constitution and the tribe's gaming compact with the state.

Under the federal Indian Gaming Regulatory Act, tribes can only offer games that are legal within the state where they are operating. The Idaho Constitution prohibits poker.

"It's my duty to enforce and defend the constitution and the laws of Idaho," Otter said in a statement. "Despite discussions with tribal leaders and our best efforts at avoiding this situation, we have no choice but to act."

Wasden will lead the legal challenge.

"I back Governor Otter and share his belief that the state-tribal compact negotiated more than 20 years ago clearly prohibits any kind of poker," Wasden said.

Officials for the Coeur d'Alene Tribe and the tribe's casino did not immediately return telephone calls seeking comment.

The casino has been a major success for the tribe, and has grown repeatedly since it first opened some two decades ago. The tribe has offered slot machines, bingo and off-track betting. The casino also includes a hotel and golf course.

The tribe planned to offer poker at six tables in a new poker room.

In the past, tribal officials have contended that poker is a game of skill with players competing against each other, with no house bank involved. For that reason, the tribe has said it is not violating its compact with the state.

Casino executives have said they are losing business to tribal casinos and commercial card rooms in Washington, which offer card games.